Incidence and onset of PCT. (A) Pilot study of tumor development in C.IL6/iMyc^Eμ (▵) and C.IL6/iMyc^Cα (○; n = 10 for both genotypes). (B) Survival studies of C.IL6/iMyc^Eμ mice (n = 12) and C.iMyc^Eμ mice (n = 20). Tumors arising in C.IL6/iMyc^Eμ mice were invariable PCT. Most tumors developing in C.iMyc^Eμ mice were high-grade B-cell lymphoma. (C) Survival studies of C.IL6/iMyc^Cα mice (n = 21) and C.iMyc^Cα mice (n = 24). All tumors in C.IL6/iMyc^Cα mice were PCT. Most tumors from C.iMyc^Cα mice were high-grade B-cell lymphoma. Transfer of the iMyc^Cα TG from the original, mixed background that exhibited approximately 9% of tumors by 12 months of age¹³  onto strain C caused a dramatic increase in tumor incidence with minimal impact on tumor phenotype.